Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
  • C08G69/44—Polyester-amides

Definitions

• the invention relates to thermoplastically processable elastomeric block copolyetheresteretheramides, a process for producing them and their use for the production of shaped articles. Production takes place, in particular, by extrusion, injection molding, coinjection molding, injection welding, or blow molding.
• the block etheramides of the invention such as the polyetherpolyamides described in DE-PS 30 06 961 or the polyetheresteramide block copolymers (polyetheresteramides) described in DE-PS 25 23 991, belong to the category of polyamide elastomers (PA-elastomers).
• PA-elastomers polyamide elastomers
• block copolyetheresteretheramide emphasizes that the polyether contents of the products according to the invention are linked to the polyamide segments by ester or amide bonds.
• PA-elastomers will be used herein.
• PA-elastomers found in the market nowadays undoubtedly include those whose polyamide segments --CO--D--CO-- had resulted from the polymerization or the polycondensation of caprolactam, laurolactam, or the corresponding ⁇ -amino- ⁇ -carboxylic acids in the presence of a dicarboxylic acid.
• PA-segments having terminal carboxyl groups are esterified with ⁇ , ⁇ -dihydroxypolyethers and the polyetheresteramides are thus obtained.
• PA-segments are reacted with ⁇ , ⁇ -diamino polyethers to form polyetheramides.
• Both methods of synthesis of PA-elastomers are subject to a number of restrictions; hence, a highly flexible PA-6-elastomer having a flexural modolus of elasticity of less than about 200 N/mm 2 (measured in the dry state) and acceptable properties for processing and use cannot be produced by the batch processes according to the teachings of either of these references.
• DE-PS 25 23 991 describes various linear or branched aliphatic polyoxyalkylene glycols as components which have a flexibilizing effect, in particular the following:
• Polyoxypropylene glycol (II) can, if its average molar mass exceeds the value of 1000 required for highly flexible, readily processable PA-6-elastomers, be mixed only to a limited extent with the respective short-chain, carboxyl-terminated PA-6-segments (Mn ⁇ 1300), so a high molecular weight polymer cannot be built up.
• a further distinct disadvantage, at least for batchwise production processes, is that polyoxypropylene glycol is very sensitive to elevated temperatures and tends to discolor and decompose under the normal polycondensation conditions. In addition, it can only be esterified with difficulty due to its individual secondary alcohol function.
• Polyoxytetramethylene glycol (III) is poorly miscible with PA-6-segments, which limits the potential polymers to less flexible products.
• the drawbacks mentioned with regard to I and II also apply to IV.
• PA-6-elastomers can be produced by condensation of PA-6 containing terminal carboxyl groups with
• V ⁇ , ⁇ -diamino-poly-(oxy-1,2-propylene) or
• an industrial, hydrogenated or non-hydrogenated, dimerized fatty acid or "dimeric acid” containing 36 carbon atoms (which can contain a small quantity of trimerised fatty acid containing 54 carbon atoms) is preferably used as a chain length regulator.
• component VI for producing a highly flexible PA-6-elastomer is hindered by its poor miscibility with the PA-segments.
• diaminopolyether VI is so expensive (due to its complicated synthesis) that it cannot be considered for the commercial production of a highly flexible PA-6- or PA-12-elastomer.
• PA-12 containing terminal carboxyl groups is polycondensed with the above-mentioned components I to IV according to DE-PS 25 23 991, then the disadvantages already mentioned with regard to I, II or IV also apply.
• III flexibilizing component
• PA-12-elastomers of almost any flexibility having very good properties for processing and use can generally be produced.
• these PA-12-elastomers still have the following distinct disadvantages.
• the first disadvantage resides in the inadequate compatibility of PA-12-segments having an average molar mass higher than about 1000 and segments of the flexibilizing component III having an average molar mass higher than about 1100 in highly flexible elastomers having a content of III amounting to more than about 45% by weight.
• the lack of compatibility is revealed by the cloudy milky appearance of the PA-12-elastomers in the solidified (crystallized out) state; the strength of parts produced therefrom is diminished transversely to the processing direction owing to the delaminability of the layered structures.
• the increased susceptibility to mechanical wear, for example, the abrasion of such PA-12-elastomer products, is closely related.
• the above-mentioned disadvantages cannot be eliminated by modifying the production process.
• PA-12-elastomers are not unreservedly suitable for coinjection molding or injection welding.
• the latter process is a special injection molding process in which polymer A is injected in a conventional injection mold onto a solidified part of the same-or usually a different-polymer inserted therein. Finished articles of which the functions can be optimally adapted to the specific requirements by suitable polymer combinations are obtained in this way. For example, it is possible by this process to restrict the elasticity in a given finished article to the regions where it is actually advantageous and to keep the remainder of the article rigid. The process also affords considerable advantages in the coloring of injection moldings.
• the fundamental condition for the application of injection welding to a specific pair of polymers is good adhesive strength at the contact faces between the polymers.
• High strength interlayer adhesion is achieved because the injection molded polymer melts a thin layer of the inserted plastic part and the melts of the two materials are mixed together.
• the miscibility of the polymers must be ensured; obviously, the process fails if the polymers are incompatible.
• PA-12-elastomers with co-component III are preferably combined with other elastomers of this type or with unmodified PA-12.
• the adhesive strength achieved in these cases is generally good, but it does not meet all requirements, particularly if the molecular weight of the PA-12-elastomer is comparatively low.
• the object of the present invention is to provide new polyamide elastomers without the above-mentioned numerous disadvantages in preparation and use.
• the block copolyetheresteretheramides according to the invention cover a very wide flexibility range. Expressed in terms of the flexural modulus of elasticity--measured according to DIN 53452 on dry test pieces--this range lies between about 40 and 700 N/mm 2 .
• the products according to the invention are suitable for the production of injection molded, extruded, blow molded, coinjection or injection welded parts. Other processing methods can equally well be adopted for these products.
• the invention also relates to a process for producing the block copolyetheresteretheramides according to the invention which resides in the fact that carboxyl-terminated polyamides (component --CO--D--CO--) are polycondensed with equimolar quantities of ⁇ , ⁇ -dihydroxypolyoxytetramethylene (component --O--E--O--) or ⁇ , ⁇ -diaminopolyoxy-1,2-propylene (component --NH--F--NH--).
• the CO--D--CO group is reacted with either the O--E--O group or the NH--F--NH group.
• the two resulting materials are then copolymerized to form the final product.
• the carboxyl-terminated polyamides are preferably obtained from lactams containing 6 to 12 carbon atoms, or from linear ⁇ -amino- ⁇ -carboxylic acids containing 6 to 12--especially 11 and 12--carbon atoms and dicarboxylic acids containing 6 to 36 carbon atoms for forming terminal carboxyl groups. It is preferably to use caprolactam and laurolactam and, as the ⁇ -aminocarboxylic acid, ⁇ -aminoundecanoic acid, ⁇ -aminolauric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and dimerized fatty acid.
• Processes for producing carboxyl-terminated polyamides are known.
• Various processes for linking these polyamides to ⁇ , ⁇ -dihydroxypoly-(oxytetramethylene) to the corresponding etheresteramide partial structure are also known.
• the process is usually carried out under reduced pressure at temperatures of between 200° and 280° C. in the presence of effective esterification/-transesterification catalysts.
• Tin(II)-compounds for example Tin(II)-oxide, Tin(II)-salts of mono- or dicarboxylic acids, as well as zirconium compounds, for example Zr-tetraisopropylate are suitable, among others, as catalysts.
• the etheramide partial structure is also formed in the above-mentioned temperature range.
• the partial structures can be built up in succession or simulataneously.
• the synthesis of one of the two or both partial structures can also take place simultaneously with the build-up of the polyamide segments --CO--D--CO. This shows that numerous variations of the process are possible. The examples demonstrate this more fully.
• the block copolyetheresteretheramides according to the invention can be modified with other polymers and can exist as a mixture with copolyolefins bearing one or more carboxyl, carboxylate, and carboxylic acid anhydride groups and other polar molecular radicals. They can very easily be mixed, for example, with grafting products of ethylene/propylene or ethylene/propylene/diene copolymers and maleic acid anhydride. In this, they are comparable to the PA-elastomers of the prior art, as described in CH-PS 655 941.
• the melt index, flexibility, notched impact strength, and processibility of PA-elastomers can be positively influenced by the addition of, for example, polar copolyolefins.
• the PA-elastomers according to the invention can obviously contain the usual additives such as anti-oxidants, UV-stabilizers, antistatic agents, conductive carbon black, flame-retardant additives, etc.
• the relative viscosities of the products have been measured in accordance with DIN 53727 using 0.5% solutions in m-cresol at 25° C. Mechanical properties were measured on dry test bars; the flexural modulusof elasticity according to DIN 53452, the notched impact strength accordingto DIN 53453, and the tensile strength and elongation at break according toDIN 53455. The melting temperatures (maxima) were measured using a DSC device, model 990 produced by DuPont. All other tests are described in theindividual examples.
• Thechain length regulator of the PA-6-segments is non-hydrogenated dimeric acid having a molar mass of 570 g/mole (Pripol 1013 produced by Unichem), the flexibilizing component is an ⁇ , ⁇ -diaminopoly(oxy-1,2-propylene) having an average molar mass of 1980 g/mole (Jeffamin D 2000 produced by Texaco). 0.3% (24 g) of antioxidant (Irganox 1330 produced by Ciba-Geigy) is added to the individual reaction mixtures in each case.
• antioxidant Irganox 1330 produced by Ciba-Geigy
• the block copolyetheramides are produced by pouring all components, together with 0.5 liter of water, into a steel autoclave with stirrer, temperature indicator, and the other necessary devices.
• the autoclave is thoroughly purged with pure nitrogen and then sealed.
• the reactants are heated to 260° C. with stirring, and the internal pressure is adjusted to about 18 bar. This pressure is maintained for two hours and isthen reduced to atmospheric pressure in the course of one hour by slowly opening the autoclave. Polycondensation is subsequently carried out for eight hours with passage of dry nitrogen. At the end, the polymer is extruded through a die and the strand of melt is granulated after cooling in a water bath.
• Test bars were injection molded from batch 1.1 and their flexural modulus of elasticity was determined to be 410N/mm 2 . Batches 2 to 5 could notbe injection molded. These products demonstrate that highly flexible PA-6-elastomers cannot be obtained by this method.
• DE-PS 2523 991 The general formula of these products corresponds to that given in DE-PS 2523 991.
• DE-PS 25 23 991 does not claim dimerized fatty acid, of the type used here, as co-component.
• a titanium compound as esterification catalyst according to DE-PS 25 23 991 a substantially more effective tin-(II)-compound according to DE-OS 34 28 404 is used in this case.
• the autoclave is closed immediately afterwards and nitrogen is introduced to a gauge pressure of about 1 bar.
• the components are stirred for one hour at 250° to 255° C.
• the pressure is then released and a vacuum is applied immediately after normalpressure has been achieved.
• An internal pressure of 1/mbar is reached within about one hour. Polycondensation is carried out for 6 hours at thispressure and at a product temperature of 250° C.
• the block copolyetheresteramide obtained is then quenched and granulated.
• the melt of the product is milky/cloudy, and opaque and yellowish in the solidified state.
• the relative viscosity is 1.54, the maximum melting point is 212° C., and 3.95 kg (14.1% based on caprolactam used) of the caprolactam is distilled off during polycondensation.
• a block copolyetheresteramide is produced from 28 kg of caprolactam, 8.28 kg of Pripol 1013, and 14.53 kg of Terathane 1000.
• the relative viscosity of the product thus obtained is 1.65
• the molar mass of its PA-segments is 2160 g/mole (corresponding to aloss of 3.9 kg of caprolactam during polycondensation and 0.9% by weight ofcaprolactam in the polymer; see Test 2.1).
• test bars The measurement of the flexural modulus of elasticity on injection molded test bars yielded a value of 255 N/mm 2 .
• the test bars exhibited layers which could easily be removed mechanically but not in such a pronounced fashion as in product 2.1.
• Comparison Example 2 shows that useful, highly flexible PA-6-elastomers cannot be obtained by this method.
• Test 3.1 (to be compared with Comparison Example 1 and Test 2.1)
• a block copolyetheresteretheramide is produced from 28 kg of caprolactam, 8.28 kg of Pripol 1013, 6.25 kg of Jeffamin D 2000, 9.04 kg of Terathane 1000, and 4 kg of Terathane 2000 using 100 g of Tin(II)-dioctoate (catalyst) and 150 g of Irganox 1330 (antioxidant).
• caprolactam, Pripol 1013, Jeffamin D 2000, and Irganox 1330 arepoured into steel autoclaves and heated to 255° C. with stirring andthe passage of nitrogen. The reactants are kept at this temperature for 2 hours.
• the product was substantially transparent as a granulate. It did not exhibit layered structures or delamination/fibrillation either in the formof extruded strands or injection molded test bars. Its flexural modulus of elasticity was 140 N/mm 2 ; a value of 560 N/mm 2 was measured at -40° C. The elastomer did not exhibit a breakage to -40° C. in the test to measure the notched impact strength.
• Test 3.2 (to be compared with Comparison Example 1 and Test 2.2)
• a block copolyetheresteretheramide is produced from 28 kg of caprolactam, 8.28 kg of Pripol 1013, 6.25 kg of Jeffamin D 2000, and 11.04 kg of Terathane 1000 under the conditions given for Test 3.1; the catalyst and antioxidant are also the same as in Test 3.1.
• this elastomer corresponded to the product of Test 3.1.
• each product is treated in finely divided form - for example as a granulate - at a temperature slightly below its melting point under vacuum or under dry nitrogen.
• the viscosity of the melt increases considerably, but its milky/cloudy appearance does not change.
• a portion of the melt is pressed in a suitable mold to a 3 mm thick slab and is caused to solidify by slow cooling.
• the slab is white and opaque.
• the remainder of the melt is poured onto a metal plate as a strand having a cross section of 10 to 40 mm 2 and is cooled.
• the strand obtained in this way does not differ in appearance from the pressedslab.
• Some test bars, 1 cm wide and about 8 cm long, are cut from the slab.
• the flexural modulus of elasticity of the elastomer is determined as about 55N/mm 2 .
• this PA-12 elastomer is useless for the production of extruded or injection molded parts owing to the defective transverse strength of the strands which, after applying a cut longitudinally to the direction of flow, could easily be torn over an average length of more than 5 cm (similarly to the products of Comparison Example 2).
• a pronounced fibrillar structure could be detected at the dullcrack faces. The shearing force acting upon the melt during the pouring of the strands was sufficient to expose the melt to such pronounced extensional deformation that a fibrillar structure was produced.
• a block copolyetheresteretheramide is produced under the same reaction conditions as in Comparison Example 4 from 88.5 g of ⁇ -aminolauric acid, 16.92 g of 1,12-dodecanedioic acid, 103.67 g of Terathane 2000, and 55.32 g of Jeffamin D 2000.
• 0.5 g of Tin(II)-dibenzoate is used as the catalyst and 0.75 g of Irganox 1330 as the antioxidant.
• the flexural modulus of elasticity of the product was 53N/mm 2 .
• the strands had a much higher transverse strength than the elastomers from Comparison Example 4. They did not exhibit a fibrillar structure which would have enabled a crack longer than about 1 cm parallelto the direction of flow to be formed. Instead, the cracks swerved to the side. In contrast to Comparison Example 4, the crack faces were not dull but glossy.
• the more rigid product (5-1) is obtained from 36.7 kg of laurolactam, 1.27 kg of 1,12-dodecanedioic acid, and 5.5 kg of Terathane 1000.
• the quantity of catalyst used Tin(II)-dioctoate) is 90 g, and 100 g of Irganox 1330 serves as the antioxidant.
• the lactam and the dicarboxylic acid are initially melted in a 100 liter autoclave under nitrogen and the mixture obtained is homogenized by stirring. The two components are then reacted within four hours at 285° C. to 290° C. to form the corresponding carboxyl-terminated polyamide.
• the relative viscosity of the elastomer was 1.93. At a rate of 200 mm/min, its tensile strength was 33N/mm 2 and its elongation at break was 255%.
• the more flexible product (5-2) is obtained in a similar manner from 30 kg of laurolactam, 2.57 kg of 1,12-dodecanedioic acid, and 12 kg of Terathane.
• the product After 60 minutes of polycondensation, the product was formed with a relative viscosity of 1.963. Its tensile strength was 35N/mm 2 and itselongation at break was 285 to 290%.
• Half tensile test specimens (10 mm wide and 4 mm thick) are initially produced from the material of Test 5-1 to measure the adhesion strength between the two elastomers.
• half of the injection mold is filled with a suitably adapted piece of metal.
• the polymer 5-1 is injection molded under the following conditions:
• the tensile test specimens of 5-1 are then inserted into the mold instead of the piece of metal.
• the elastomer 5-2 is then injected onto them under the following conditions:
• a tensile test is carried out on the parts composed of Tests 5-1 and 5-2, under the same conditions. A tensile strength of 16.4 N/mm 2 is found with an elongation at break of 35%.
• the PA-12-elastomer 5-3 produced from 30 kg of laurolactam, 3.65 kg of dodecanedioic acid, 10.15 kg of Terathane 1000, and 2.25 kg of ⁇ , ⁇ -diamino-poly(oxy-1,2-propylene) having an molar mass of 425 g/mole (Jeffamin D 400 produced by the company Texaco), by a process similar to that employed in Test 5-2.
• the elastomer was formed with a relative viscosity of 1.957.
• 5-3 is processed under the following conditions:
• Tensile testing of the elastomer assembly 5-1/5-3 yields a tensile strengthof 16.7 N/mm 2 and an elongation at break of 157%. Energy at break is between 300 and 400% above the values of the combination of materials 5-1/5-2 (Comparison Example 5) as is determined from the respective stress/strain graphs by integration.
• This Example shows that the flexibility can be increased by adding polyolefin elastomers of the type used here to the polyamide elastomers according to the invention.

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• 1989
  • 1989-05-24 DE DE3917017A patent/DE3917017A1/de active Granted
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